In a recent study published in JAMA Oncology, researchers evaluated the relationship between device-monitored, vigorous, intermittent lifestyle physical activity (VILPA) and cancer incidence. They estimated the minimal dosage needed for a 50% risk reduction.
Study: Vigorous Intermittent Lifestyle Physical Activity and Cancer Incidence Among Nonexercising Adults. Image Credit: siam.pukkato/Shutterstock.com
Background
VILPA refers to brief and sporadic (e.g., ≤1.0 to 2.0 minutes) bouts of vigorous PA (VPA) during everyday living, e.g., bursts of stair climbing or brisk walking.
The relationship between the PA intensity and sites of certain cancers, such as colon and breast tumors, depends on the dosage and has greater risk reductions related to VPA compared to lower intensities.
Vigorous PA can help achieve the recommended PA levels to prevent cancer in a time-efficient manner; however, structured longer VPA bouts (through conventional exercise) may be inaccessible or unappealing to middle-aged adult individuals.
About the study
In the present prospective cohort study, researchers investigated whether VILPA in brief bouts (≤1.0 and 2.0 minutes) has a dose-response relationship with new-onset cancer among inactive adults.
The study included 22,398 physically inactive adult participants of the United Kingdom Biobank (UKBB) accelerometry study followed through October 30 2021 (hospitalizations and mortality) or June 30 2021 (tumor registrations). The study exposures were regular VILPA of ≤1.0 and 2.0 minutes, measured using accelerometers worn by the participants on their dominant wrist.
The main outcome measures were the physical activity-associated and total cancer incidences (a composite measure including 13 tumor locations related to low physical activity levels). Only inactive individuals who documented no exercise during their leisure time and ≤1.0 recreational walks weekly were included in the analysis.
The team excluded individuals with missing covariate data, prevalent or prior tumors in the remission phase, tumor events during the initial year after baseline evaluation, or inadequate accelerometer wear time.
The team classified PA intensity using validated two-stage random forest classifiers based on machine learning into light-intensity PA (LPA), moderate-intensity PA (MPA), and VPA. Cancer incidence was described as tumor registrations and tumor-related hospitalization or mortality, excluding in situ non-melanoma skin tumors and poorly defined tumors.
Poisson regression was used for the analysis, and hazard ratios (HRs) were calculated with data adjustments for participant age, body mass index (BMI), education, sex, smoking habits, alcohol intake, medications, cardiovascular disease prevalence, sleep durations, vegetable and fruit intake, parental history of cancer, MPA and LPA, and vigorous physical activity from >1.0- and 2.0-minute bouts.
Results
Among the sample population of 22,398 individuals, the mean age was 62 years; 45% (n=10,122) were male; 55% (n=12,276) were female; and 96% (n=21,509) were Whites.
Over seven years of follow-up (corresponding to 149,650 individual years), 2,356 new-onset cancer events were reported, of which 1,084 were due to physical activity-associated cancer. Ninety-two percent of vigorous intermittent lifestyle PA resulted from ≤1.0-minute bouts, and 97% of the bouts were ≤2.0-minute-long.
Regular VILPA duration showed an almost linear association with outcomes, with steeper dosage-response curvatures for physical activity-associated cancer compared to the total cancer incidence. Compared to no vigorous intermittent lifestyle physical activity, the median (4.50 minutes daily) everyday vigorous intermittent lifestyle physical activity duration of ≤1.0-minute bouts was related to HR values of 0.7 and 0.8 for physical activity-associated and total cancer, respectively.
The minimal dosages were 3.7 and 3.4 minutes daily for physical activity-associated and total cancer incidences, respectively. Similar findings were obtained for the vigorous intermittent lifestyle physical activity bout of ≤2.0 minutes.
In addition, the sensitivity analyses yielded similar results, performed by excluding underweight or poor-health individuals and those who reported an event during the initial two years and excluding body mass index from the modeling.
Proof-of-concept studies have demonstrated that small durations of intermittent vigorous PA may rapidly improve cardiorespiratory fitness, providing a biological basis for the relationships with new-onset cancer mortality.
The biological pathways associating physical activity with incident cancer include inflammation, body composition, endogenous sex hormones, and insulin resistance.
Overall, the study findings showed that three to four minutes of vigorous and intermittent lifestyle physical activity daily reduced cancer incidence by 17.0% to 18.0%. A 4.5-minute VILPA (median) daily lowered PA-associated cancer incidence by 31.0% to 32.0%.
Based on the findings, VILPA holds promising potential as a cancer prevention strategy among individuals unmotivated or unable to engage in physical activities in their leisure time.
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